Unique Muskoka August

On high alert
for ash borers
Article by Dawn Huddlestone
Photograph: Daniel Herns, The Ohio State University, Bugwood.org Photograph: Penn. Dept. of Conserv. and Nat. Resources
It’s a lean, green, eating machine and it’s
making its way to Muskoka. When it
does, it could have devastating
effects on our local ash population.
The emerald ash borer is a
small – about one centimetre
long – metallic green, bulletshaped
beetle that attacks all
true species of ash (Fraxinus
spp.). It was discovered in the
County of Simcoe in 2013
and has been found on
Manitoulin Island and in Sault Ste.
Marie. Traps have been set in Bracebridge’s
Kerr Park, in a partnership between the
Muskoka Conservancy and the Town of
Bracebridge, to determine if the beetle has
arrived in Muskoka.
“The beetle is lethal to ash trees,” says
Allison Winmill, a forest health specialist
with BioForest Technologies, who helped to
set the traps. “If left untreated, an
infested tree will die.”
It’s the beetle’s larvae that
does the most damage, says
Winmill. “The adult female
will lay her eggs on the bark
of the tree. When they hatch,
the larvae then tunnel into
the cambial layer of the tree
(its growing layer) and begin to
feed. They chew in a characteristic
“S” or serpentine pattern, which causes the
vascular tissue to become compromised by
preventing the flow of essential water and
nutrients between the leaves in the crown
and the roots. The larvae overwinter under
the protective bark, and in the spring the
adult beetle emerges and the cycle begins
again.”
By the time it’s apparent the tree is in
distress, it has already experienced severe
internal damage. Early detection of the beetle
is crucial, which is why green prism traps
have been hung in Bracebridge. They use a
“green leaf volatile in combination with a
pheromone to attract the beetles, which then
stick to the trap,” says Winmill.
Emerald ash borers migrate slowly on
their own – only a few kilometres per year,
according to Ontario’s Invading Species
Awareness Program – but they can travel in
infested wood products like firewood, lumber
and wood chips.
“For Muskoka, this is a big concern,” says
Winmill. “People should not be transporting
firewood around the province to try and
Left: The beetle’s larvae do the most damage.
When they hatch, the larvae tunnel into the
cambial layer of the tree and begin to feed, which
prevents the flow of essential water and nutrients
in the tree. Top left: About one centimetre in length,
the emerald ash borer is a metallic green,
bullet-shaped beetle that attacks all true species
of ash. Top right: Traps have been set in
Bracebridge in a partnership between the
Muskoka Conservancy and the Town of
Bracebridge, to determine if the beetle has
arrived in Muskoka.
August 2016 UNIQUE MUSKOKA 13
Photograph: Allison Winmill